Tooke me over two hours to get to work today due to combo of rain and stupid drivers. On my luxurious commute through Newark I heard an intresting news story. The peice was on Poison Ivy and how rising carbon dioxide in the atmosphere are leading to an icrease in the spread of poison ivy. Also increaded carbon dioxide emmisons have also increased the level of the rash causing toxicity.
Here is one article on the topic you may want to google search for additional information on the topic.
Pumped-up Poison Ivy: Carbon dioxide boosts plant's size, toxicity: Science News Online, June 3, 2006